1. Field of the Invention
The present invention relates to micro-electromechanical systems (MEMS) and, more specifically, to MEMS-based safety and arming devices.
2. Description of the Related Art
An artillery shell is typically equipped with a safety and arming (S&A) device that permits detonation of the explosive charge only after the projectile has experienced a valid progression of physical launch conditions, including the large initial acceleration in the gun barrel. The S&A device functions with sequential interlocks to remove a barrier in the fire train and/or to move out-of-line fire-train components into alignment. Once armed, the device permits initiation of the explosive, e.g., with an electrical discharge or a laser pulse, which initiation eventually causes the explosive to detonate.
U.S. Pat. No. 6,167,809, which is incorporated herein by reference in its entirety, discloses a mechanical S&A device that is assembled using several separately manufactured components, such as screws, pins, balls, springs, and other elements machined with relatively tight tolerance. One problem with that device is that it is relatively large (e.g., several centimeters) in size and relatively expensive to manufacture and assemble. Each of U.S. Pat. Nos. 7,142,087 and 7,218,193, both of which are also incorporated herein by reference in their entirety, discloses a MEMS-based S&A device formed using a silicon wafer. While the latter devices are advantageously relatively small (e.g., about 1 mm) in size and relatively inexpensive to manufacture, they are not specifically designed for withstanding very hard launches, e.g., those causing initial accelerations of over 50,000 g.